Implantable Loop Recorder Implantation Research Articles

Real-world utility of implantable loop recorders

Abstract Background Implantable loop recorders (ILRs) allow prolonged and continuous single-lead electrocardiogram recording and have significantly shortened time to electrocardiographic diagnosis and appropriate therapy of many bradyarrhythmias and tachyarrhythmias. Purpose The aim of this retrospective single center study was to evaluate ILR indications, diagnostic yield and ILR-guided interventions. Methods We retrospectively analyzed 388 patients (223 male / 165 female), who underwent Medtronic and Biotronik ILRs implantation at a heart center. Demographic and clinical data were obtained from the medical records. Remote monitoring was analyzed when no data of in-hospital follow up could be acquired. Results The mean age at ILR implantation was 63.4 ± 14.9 years with a mean follow-up of 20.7±17.6 months from ILR implantation. In total, 152 (39.2%) patients were followed by a remote monitoring system. Number of patients with ILR indication due to syncope (n=171; 44.1%) was significantly higher compared to patients with monitoring after ablation of atrial fibrillation or atrial flutter (n=108; 27.8%), cryptogenic stroke (n=50; 12.9%) and presyncope and dizziness (n=21; 5.4%) (p<0.05). After 12 months, arrhythmia was detected in 198 cases (79.2% out of 250 patients with detected arrhythmias). The most common type of arrhythmia was paroxysmal atrial fibrillation (31.7%) with a significantly higher prevalence compared to atrial tachycardias (16.5%) and supraventricular premature beats (9.8%) (p<0.05). Noteworthy, in 132 (52.8% out of 250) patients, ILR diagnosis corresponded to the suspected arrhythmia, whereas in 118 patients unexpected arrhythmias were detected. ILR diagnosis of arrhythmia lead in 147 (58.8%) patients to initiation of a new therapy or to a change of current medication. Changes of current medication occurred in 72 patients (28.8%), electrophysiology study/ablation in 66 patients (26.4%), pacemaker/ICD implantation in 46 (18.4%), electrical cardioversion in 6 patients (2.4%), and closure of the left atrial appendage in 1 patient. Conclusion Our study shows, that ILRs are an important diagnostic tool, providing clinical relevant data in about two thirds (65%) of the patients. About half (52.8%) of the detected arrhythmia correlated with the symptoms leading to ILR implantation (number needed to treat was around 2). Remote monitoring improves the diagnostic timing with a potential reduction of costs for health care. However, patient selection is critical and ILRs benefits needs to be proven in larger randomized trials.

Real-world evaluation of the treatment yield of implantable loop recorders (ILR) in the Netherlands

Abstract Background Implantable loop recorders (ILRs) are invasive and expensive diagnostic tools used to determine the underlying arrhythmias associated with syncope and palpitations as well as capture atrial fibrillation (AF). The diagnostic and treatment yield from ILRs is uncertain. Prior studies indicated that 26-52% ILR patients were diagnosed with arrhythmias and 11-30% received subsequent treatment. Purpose Our primary aim was to determine the incidence of pacemaker and ICD implants within 1- and 3- years of ILR implantation. The secondary aims include 1) an evaluation of the incidence of AF ablation, 2) the identification of predictors for treatment, and 3) safety. Methods Adult patients who underwent an ILR implant in the Netherlands Heart Registration (NHR) Pacemaker and ICD registry (2018-2021) were included. The NHR device registry was linked to the ablation registry to determine the incidence of AF ablation after ILR. Incidence rates for pacemaker implants, ICD implants, AF ablations, and complications among ILR patients were reported as a proportion of ILR patients over 1- and 3- years. Predictors for treatment following an ILR were determined from multivariable logistic regression models. Results From 2018 to 2021, 11,961 patients underwent an ILR implant in the Netherlands. Patients who underwent ILR implantation were a median age 69 (IQR 56-77) years, 46.9% female, and 24.9% had AF. The most frequent indication for ILR implantation was syncope (76.2%), followed by palpitations (15.2%). At 1- and 3-years post-ILR implantation, 12.0% and 14.6% of ILR patients underwent a pacemaker implant, respectively (Figure 1). Fewer patients underwent ICD implants (0.9% and 1.3%) and AF ablation (1.3% and 1.8%) at 1- and 3-years post-ILR implantation, respectively (Figure 1). Compared to males, females were 28% and 70% less likely to undergo a pacemaker and ICD implant following ILR, respectively (Figure 2). Additional predictors for pacemaker implantation included older age, AF, and syncope (p<0.05 for all, Figure 2a). In addition to female sex, AF was a predictor of ICD implantation (Figure 2b). The incidence of complications was relatively low (0.3%). Infection was the most frequent complication (0.2%), followed by device dislocation (0.06%), bleeding (0.02%), and device defect (0.01%). Conclusion Despite the benefits of ILRs for long-term remote monitoring, the therapeutic yield of ILRs is relatively low with 14.6%, 1.3%, and 1.8% of ILR patients undergoing implantation for pacemakers, ICDs, and AF ablation at 3-years follow-up. As an expensive and invasive diagnostic tool, a more targeted approach for referrals is warranted to increase the therapeutic yield of the ILRs. Further investigations are warranted to determine the diagnostic yield of ILRs, regardless of subsequent invasive therapy.

Impact of an expanded reimbursement policy on utilization of implantable loop recorders in patients with cryptogenic stroke in Korea.

The reimbursement policy for cryptogenic stroke (CS) was expanded in November 2018 from recurrent strokes to the first stroke episode. No reports have demonstrated whether this policy change has affected trends in implantable loop recorder (ILR) utilization. We identified patients who received an ILR implant using the Korea Health Insurance Review and Assessment Service database between July 2016 and October 2021. Patients meeting all the following criteria were considered to have CS indication: 1) prior stroke history, 2) no previous history of atrial fibrillation or flutter (AF/AFL), and 3) no maintenance of oral anticoagulant for ≥4 weeks within a year before ILR implant. AF/AFL diagnosed within 3 years after ILR implant or before ILR removal was considered ILR-driven. Among 3,056 patients, 1,001 (32.8%) had CS indications. The total ILR implant number gradually increased for both CS and non-CS indications and the number of CS indication significantly increased after implementing the expanded reimbursement policy. The detection rate for AF/AFL was 26.3% in CS patients over 3 years, which was significantly higher in patients implanted with an ILR within 2 months after stroke than those implanted later. The expanded coverage policy for CS had a significant impact on the number of ILR implantation for CS indication. The diagnostic yield of ILR for AF/AFL detection seems better when ILR is implanted within 2 months than later. Further investigation is needed to demonstrate other clinical benefits and the optimal ILR implantation timing.

Diagnostic Yield and Clinical Implications of Implantable Loop Recorders in Patients with Syncope in Germany: A National Database Analysis.

In patients with unexplained syncope, implantable loop recorders (ILR) are used to detect arrhythmias as a cause of syncope. This study aimed to assess the diagnostic yield and clinical implications arising from ILR implantation in patients with syncope in Germany. Secondary longitudinal data were obtained from a large German research database including anonymized data from nationwide statutory health insurances, representative for the German population. Patients ≥ 18 years with a diagnosis of syncope and ILR implantation between 2017 and 2018 were analyzed, and cardiac diagnoses and therapies during a follow-up period of two years assessed. Of 2,403,301 continuously insured persons in 2017-2018, 1360 (0.1%) received an ILR and 675 patients (45.6% female) were included. During follow-up, arrhythmias were diagnosed in 65.0%. The following antiarrhythmic therapies were established: pacemaker and defibrillator implantations in 20% and 1.5%, respectively, ablation therapy in 3.0%, and antiarrhythmic drug therapy in 4.7%. Aside from the diagnoses typically associated with syncope, atrial fibrillation or flutter was diagnosed in 37.0%, and anticoagulation therapy was initiated in 21.5%. There was a high diagnostic yield of arrhythmias following ILR implantation, leading to a relevant number of syncope-specific treatment. Arrhythmias not necessarily related to syncope were also diagnosed, leading to a high rate of anticoagulation therapy.

Predictors of atrial fibrillation detection in embolic stroke of undetermined source patients with implantable loop recorder.

Covert atrial fibrillation (AF) is a predominant aetiology of embolic stroke of undetermined source (ESUS). Evidence suggested that AF is more frequently detected by implantable loop recorder (ILR) than by conventional monitoring. However, the predictive factors associated with occult AF detected using ILRs are not well established yet. In this study we aim to investigate the predictors of AF detection in patients with ESUS undergoing an ILR. This observational multi-centre study included consecutive ESUS patients who underwent ILR implantation. The infarcts were divided in deep, cortical infarcts or both. The infarction sites were categorized as anterior and middle cerebral artery, posterior cerebral artery with and without brainstem/cerebellum involvement. Multivariable logistic regression analysis was performed to investigate variables associated with AF detection. Overall, 3,000 patients were initially identified. However, in total, 127 patients who consecutively underwent ILR implantation were included in our analysis. AF was detected in 33 (26%) out of 127 patients. The median follow-up was 411 days. There were no significant differences in clinical characteristics and comorbidities between patients with and without AF detected. AF was detected more often after posterior cerebral artery infarct with brainstem/cerebellum involvement (p < 0.001) whereas less often after infarction in the anterior and middle cerebral artery (p = 0.021). Multivariable regression analysis demonstrated that posterior cerebral artery infarct with brainstem/cerebellum involvement was an independent predictor of AF detection. Our study showed that posterior circulation infarcts with brainstem/cerebellum involvement are associated with AF detection in ESUS patients undergoing ILR. Larger prospective studies are needed to validate our findings.

Clinical utilisation of implantable loop recorders in adults with Fabry disease-a multi-centre snapshot study.

Fabry disease (FD) is an X-linked deficiency of alpha-galactosidase-A, leading to lysosomal storage of sphingolipids in multiple organs. Myocardial accumulation contributes to arrhythmia and sudden death, the most common cause of FD mortality. Therefore, there is a need for risk stratification and prediction to target device therapy. Implantable loop recorders (ILRs) allow for continual rhythm monitoring for up to 3 years. Here, we performed a retrospective study to evaluate current ILR utilisation in FD and quantify the burden of arrhythmia that was detected, which resulted in a modification of therapy. This was a snapshot assessment of 915 patients with FD across three specialist centres in England during the period between 1 January 2000 and 1 September 2022. In total, 22 (2.4%) patients underwent clinically indicated ILR implantation. The mean implantation age was 50 years and 13 (59%) patients were female. Following implantation, nine (41%) patients underwent arrhythmia detection, requiring intervention (six on ILR and three post-ILR battery depletion). Three patients experienced sustained atrial high-rate episodes and were started on anticoagulation. Three had non-sustained tachyarrhythmia and were started on beta blockers. Post-ILR battery depletion, one suffered complete heart block and two had sustained ventricular tachycardia, all requiring device therapy. Those with arrhythmia had a shorter PR interval on electrocardiography. This study demonstrates that ILR implantation in FD uncovers a high burden of arrhythmia. ILRs are likely to be underutilised in this pro-arrhythmic cohort, perhaps restricted to those with advanced FD cardiomyopathy. Following battery depletion in three patients as mentioned above, greater vigilance and arrhythmia surveillance are advised for those experiencing major arrhythmic events post-ILR monitoring. Further work is required to establish who would benefit most from implantation.

Continuous monitoring with implantable loop recorder detects arrhythmic risk in adults with systemic right ventricle following atrial switch

Abstract Background Patients with a systemic right ventricular circulation following atrial switch are at high risk of sudden death despite current monitoring strategies and advances in heart failure management. Arrhythmia represents a significant risk factor and early detection and intervention is of great value. The current surveillance approach with intermittent ambulatory monitoring is limited and cumbersome. Purpose We hypothesise that continuous rhythm monitoring with an implantable loop recorder (ILR) in the systemic right ventricle population will allow early detection of clinically significant arrhythmias. Methods Patients under follow up with a systemic right ventricular circulation following atrial switch were offered ILR implantation as an alternative to the standard of care (ambulatory 24-hour ECG). Patients with pre-existing intra-cardiac pacing devices or palliative were excluded. Following implantation, recordings made with symptoms or automatically following detection of significant arrhythmias. This included pauses over 3 seconds, atrioventricular block or supraventricular tachycardia. Transmission were reviewed daily and significant findings discussed in an adult congenital heart disease and electrophysiology MDT. Patients otherwise had routine clinical care. Results 24 patients had implantation of a loop recorder (67% of eligible cohort). They were aged 29-49 years (median 35 years) and 50% had additional lesions. Right ventricular function was normal in 42% and 29% had moderate or severe tricuspid regurgitation. 75% of the cohort were NYHA classification I. All but one patient were in sinus rhythm and 8 (33%) had previous intra-atrial re-entry tachycardia (IART). No patient had previously documented significant conduction disease. Implants were undertaken over 6 years without complications. 18 patients (75%) had automated or symptom activated recordings (52% automated) with a median of 2.8 recordings per patient (range 0 – 8 per patient) over 39.5 months (1.6 – 72.5 months). The recordings were clinically significant in 64% of the cohort (Table). This included 2 (9% of entire cohort) patients with atrioventricular block only, 11 patients (46%) with IART only and 4 patients (17%) with both IART and conduction disease (1 with atrioventricular block). These recordings resulted in 5 pacemaker implants (3 for atrioventricular block) and 2 further patients declined a device (1 subsequent death). 4 patients underwent, or are awaiting, ablation for IART. Risk scoring for sudden death did not predict arrhythmia events or atrioventricular block (1) (Figure). Conclusions Empirical ILR implantation in this low-risk systemic right ventricle cohort was well tolerated and detected a high burden of significant arrhythmias requiring intervention. Arrythmias were not predicted by risk scoring. This monitoring approach is an effective alternative to intermittent ambulatory surveillance however the impact on sudden death is unclear.

Implantable loop recorder monitoring in inherited cardiomyopathies: yield of clinically relevant arrhythmias

Abstract Background Implantable loop recorders (ILRs) are a minimally invasive tool for the diagnosis of arrhythmias in patients with unexplained syncope or asymptomatic arrhythmias. Their use in patients with inherited arrhythmia syndromes has been recommended in the recent 2022 ESC Guidelines (1). However, the clinical utility of ILRs in patients with inherited cardiomyopathies remains unexplored. Purpose The purpose of this study was to evaluate the yield of ILR monitoring in detecting clinically relevant events in a single cohort of patients with inherited cardiomyopathies. Methods We prospectively collected demographic, clinical, and follow-up data from patients with inherited cardiomyopathies (Arrhythmogenic Cardiomyopathy, ACM; Hypertrophic Cardiomyopathy, HCM; Dilated Cardiomyopathy, DCM; Left Ventricular Non-Compaction, LVNC) who were implanted with an ILR and were followed with telemedicine. The primary endpoint was a clinically significant event recorded with the ILR that required an update to an implantable cardioverter defibrillator (ICD). Results The study cohort included 53 consecutive patients (55% males; mean age at ILR implantation 35±14 years) with inherited cardiomyopathies: 33/53 (62%) with ACM, 9/53 (17%) with HCM, 7/53 (13%) LVNC, 4/33 (8%) DCM. None of the patients implanted had previously experienced life-threatening arrhythmias. During a median follow-up of 2.6 years (IQR 1.4-3.7 years) after ILR implantation, clinically relevant arrhythmic events were documented in 9/53 (17%) of patients. Specifically, sustained or non-sustained ventricular tachycardia episodes were detected in 8 patients (5 with ACM, 2 with LVNC, 1 with LMNA-related DCM), whereas one patient with HCM showed symptomatic pauses &amp;gt; 3 seconds due to sick sinus syndrome. In all cases, the detection of such episodes led to the upgrade to ICD implantation. Conclusions ILR monitoring of patients with inherited cardiomyopathies identified clinically relevant events in almost one-fifth of patients, suggesting that the use of ILR may substantially improve the management of these patients. Figure 1. Representative example of clinically actionable event detected by implantable loop recorder (ILR) in a patient with inherited cardiomyopathy. The patient, a 19-year-old male with a definitive diagnosis of Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) and a pathogenic PKP2 truncating variant, presented with palpitations and vertigo during physical exertion one year after the implantation of an ILR. ILR monitoring documented a rapid tachycardia with a mean frequency of 250 bpm lasting 3 minutes, prompting an indication for an implantable cardioverter defibrillator (ICD).Figure 1.

Predicting incident atrial fibrillation in patients with embolic stroke of undetermined source

Abstract Introduction Atrial fibrillation (AF) is an important potential embolic source in patients who have suffered an embolic stroke of undetermined source (ESUS). AF has been detected in over 40% of patients when monitored with an implantable loop recorder (ILR). Recent clinical trials, however, have suggested that empirical anticoagulation of all patients with an ESUS is not an effective approach to reduce stroke risk. Thus predicting which patients are most likely to develop AF is of increased importance. Risk models for predicting incident AF exist but they do not incorporate modern techniques such as advanced echocardiographic parameters to create a comprehensive risk model. Purpose We sought to create a multi-parametric risk score for the prediction of incident AF in patients with ESUS. Methods This was a single-centre retrospective study. Consecutive adult patients referred for ILR implantation following ESUS, between March 2009 and November 2019, without prevalent AF or atrial flutter, were included. Patients’ notes were reviewed for clinical and anthropometric data. Each patients’ echo was re-reviewed both for conventional measures, and advanced parameters including left atrial strain using speckle-tracking (figure 1) and atrial electromechanical delay utilising the time from onset of the electrocardiographic P-wave to the lateral tissue Doppler A’ wave- "lateral PA". Univariate and multivariable analyses were performed, and a subsequent Lasso regression analysis used to develop a risk prediction model. Bootstrapping was used to perform internal validation. Results A total of 323 patients with ESUS who underwent a loop recorder implantation were included. Incident AF was detected in 142 patients (47.1%). Increased duration of the time between the electrocardiographic P-wave and the lateral tissue Doppler A’ wave (greater lateral PA), older age, higher diastolic blood pressure, abnormal left atrial reservoir strain were most strongly associated with increased AF risk. These were combined to form the PADS score below. Model discrimination was good, with an area under the curve of 0.72. Conclusion(s) The PADS score is a novel risk score for the prediction of incident AF in patients who have suffered an ESUS, based on the duration of the P-wave to the lateral tissue Doppler A’ wave, Age, Diastolic blood pressure and left atrial strain reservoir . Further work is required to assess whether the PADS score can be used to risk stratify patients into a high risk group which would derive benefit from immediate anticoagulation, an intermediate risk group who require prolonged continuous monitoring and a low risk group who can continue on conventional management for their stroke.PADS formulaLA strain using speckle strain analysis

An unmet need: arrhythmia detection by implantable loop recorder in the systemic right ventricle.

Patients with systemic right ventricles are at high risk of sudden cardiac death. Arrhythmia is a significant risk factor. Routine Holter monitoring is opportunistic with poor adherence. The aim of this study was to determine if continuous rhythm monitoring with an implantable loop recorder (ILR) could allow early detection of clinically important arrhythmias. Implantable loop recorder implantation was offered to patients with atrial switch repair for transposition of the great arteries. Recordings were made with symptoms or, automatically for pauses, significant bradycardia or tachycardia and reviewed by the multi-disciplinary team. Twenty-four out of 36 eligible patients underwent ILR implantation with no complication. Forty-two per cent had preserved ventricular function, 75% were NYHA functional class I, 88% had low sudden cardiac death risk, 33% had previous intra-atrial re-entrant tachycardia (IART), and none had known conduction disease. Eighteen out of 24 (75%) patients made 52 recordings (52% automated) over 39.5 months (1.6-72.5). Thirty-two out of 52 (62%) recordings in 15/24 (63%) of the cohort were clinically significant and included sinus node disease (two patients), atrioventricular block (two patients), IART (seven patients), and IART with sinus node disease or atrioventricular block (four patients). Implantable loop recorder recordings prompted medication change in 11 patients [beta-blockers (n = 9), anti-coagulation (n = 5), and stopping anti-coagulation (n = 1)] and device therapy recommendation in seven patients [five pacemakers (three: atrioventricular block) and two defibrillators]. Two patients declined intervention; one suffered an arrhythmic death. Intra-atrial re-entrant tachycardia and clinically relevant conduction disease were detected in patients irrespective of sudden cardiac death risk. Continuous monitoring with an ILR in patients with systemic right ventricle following atrial switch detects clinically relevant arrhythmias that impact decision-making. In this cohort, clinically relevant arrhythmias did not correlate with sudden cardiac death risk.

Detection of atrial fibrillation using an implantable loop recorder in patients with previous cryptogenic stroke: the SPIDER-AF registry (Stroke Prevention by Increasing DEtection Rates of Atrial Fibrillation).

The use of implantable loop recorder (ILR) to detect atrial fibrillation (AF) in patients with a history of cryptogenic stroke (CS) has seldom been investigated in "real-world" settings. This study aimed to present the results of the Stroke Prevention by Increasing DEtection Rates of Atrial Fibrillation (SPIDER-AF) registry. SPIDER is a multicentric, observational registry, including 35 facilities all over Germany. It enrolled outpatients without AF history and with CS before ILR implantation. We included 500 patients (mean age 63.1 ± 12.7years), 304 (60.8%) were males, with previous stroke (72.6%) and TIA (27.4%). After inclusion, all were followed for at least 12months. AF was detected in 133(26.8%), 25.3% of patients with previous stroke and 29.9% with TIA (p = 0.30). AF was detected after a median of 121.5days (IQR 40.5-223.0). AF was primarily paroxysmal (95.7% after stroke, 100% after TIA). In 19.5% (n = 26) anticoagulation was not administered after AF detection. Mean CHA2DS2-VASc score (OR 1.22; CI 1.01-1.49; p = 0.037) and age > 70years (OR 0.41; CI 0.19-0.88; p = 0.0020) correlated with AF. Repeat cerebrovascular events at follow-up (28; 5.6%) correlated with AF (OR = 2.17; CI 1.00-4.72; p = 0.049). AF (p = 0.91) and recurrent events (p = 0.43) occurred similarly in females and males. In the context of cryptogenic strokes ILRs are a valuable tool for early detection of AF. In a real-world scenario, the anticoagulation therapy remains inadequate despite diagnosed AF in a relevant subset of patients requiring optimization of patient management.

Atrial fibrillation in embolic stroke of undetermined source: role of advanced imaging of left atrial function.

Atrial fibrillation (AF) is detected in over 30% of patients following an embolic stroke of undetermined source (ESUS) when monitored with an implantable loop recorder (ILR). Identifying AF in ESUS survivors has significant therapeutic implications, and AF risk is essential to guide screening with long-term monitoring. The present study aimed to establish the role of left atrial (LA) function in subsequent AF identification and develop a risk model for AF in ESUS. We conducted a single-centre retrospective case-control study including all patients with ESUS referred to our institution for ILR implantation from December 2009 to September 2019. We recorded clinical variables at baseline and analysed transthoracic echocardiograms in sinus rhythm. Univariate and multivariable analyses were performed to inform variables associated with AF. Lasso regression analysis was used to develop a risk prediction model for AF. The risk model was internally validated using bootstrapping. Three hundred and twenty-three patients with ESUS underwent ILR implantation. In the ESUS population, 293 had a stroke, whereas 30 had suffered a transient ischaemic attack as adjudicated by a senior stroke physician. Atrial fibrillation of any duration was detected in 47.1%. The mean follow-up was 710 days. Following lasso regression with backwards elimination, we combined increasing lateral PA (the time interval from the beginning of the P wave on the surface electrocardiogram to the beginning of the A' wave on pulsed wave tissue Doppler of the lateral mitral annulus) [odds ratio (OR) 1.011], increasing Age (OR 1.035), higher Diastolic blood pressure (OR 1.027), and abnormal LA reservoir Strain (OR 0.973) into a new PADS score. The probability of identifying AF can be estimated using the formula. Model discrimination was good [area under the curve (AUC) 0.72]. The PADS score was internally validated using bootstrapping with 1000 samples of 150 patients showing consistent results with an AUC of 0.73. The novel PADS score can identify the risk of AF on prolonged monitoring with ILR following ESUS and should be considered a dedicated risk stratification tool for decision-making regarding the screening strategy for AF in stroke.

Detection of atrial fibrillation in real world setting in patients with cryptogenic stroke and an implantable loop recorder.

Implantable loop recorders (ILR) are used to screen for atrial fibrillation (AF) in patients with cryptogenic stroke (CS). However, there is limited real-world data regarding the long-term rate of AF detection using ILR and management consequences in patients with CS. The objective is to assess the rate of AF detection in patients with CS in a real-world study over 36 months of follow-up and its consequences on stroke prevention. This retrospective study included patients with an ILR placed for CS at Baylor College of Medicine and Baylor St. Luke's Medical Center between January 2014 and July 2021. The primary outcome was AF detection in patients with ILR. The secondary outcome was the rate of subsequent strokes after ILR placement in patients with or without diagnosed AF. The AF detection rate in our cohort was compared to the rate in CRYSTAL-AF Trial at 36-month follow-up. The impact of AF detection on clinical management was examined. We identified 225 patients. 51.1% were women and 38.2% African American. Among 85 patients with ILR labeled AF, 43 patients had true AF, and 42 had incorrectly labeled AF (48.3% false positive). The estimated AF detection rate at 36 months follow-up was 28.6% (95% CI, 26.6%-30.6%). 58.1% of patients with AF were initiated on oral anticoagulation, 80.0% of whom were started on a direct oral anticoagulant. 13.8% of patients had recurrent strokes after ILR implantation; 4 of whom were diagnosed with AF. Compared to CRYSTAL-AF, the AF detection rate in our cohort is similar, but this cohort includes a higher proportion of female and African American patients. Most patients with recurrent strokes after ILR implant did not have AF during 36 months of monitoring.

Role of the implantable loop recorder in clinical practice: insights on indications, diagnostic yield and therapeutic implications from a single, high volume, tertiary care centre experience

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Besides the established class I indication for the evaluation of patients with recurrent syncope of uncertain origin, implantable loop recorders (ILRs) have been increasingly used for other diagnostic purposes (e.g. detection of atrial fibrillation (AF) following cryptogenic stroke). Purpose To describe the main indications to ILR and to investigate procedural parameters, outcomes and diagnostic yield of ILR in a single, high-volume tertiary care centre. Methods All patients undergoing ILR implantation between November 2007 and April 2022 were consecutively enrolled in this study. Clinical characteristics of patients, procedural data and outcomes were collected. The indications to ILR implantation were divided into four categories: 1) AF detection in patients with recent cryptogenic stroke or peripheral thromboembolism [CRYSP], 2) recurrent syncope of uncertain origin [RSUO], 3) monitoring of ventricular arrhythmic events [VAE] in patients with predisposing cardiomyopathy/channelopathy, 4) monitoring of AF burden or relapse [AFB]. The main endpoint of the study was the diagnostic yield (number of definitive diagnoses made) and the time to diagnosis following ILR implantation. The occurrence of acute or subacute complications was used as a secondary safety endpoint. Results Overall, 1442 patients underwent ILR implantation (mean age 65 years, 43% female). The two main indications to ILR were AF detection following CRYSP and RSUO (42% and 34% of all implantations respectively, table 1). The commonest site of implantation was the left parasternal position (902 patients, 63%), median procedural time was 20 minutes (IQR 15-25). During a median follow-up of 397 days (134-1094), infections requiring ILR extraction or pocket revision occurred in 13 patients (0.9%). A definitive diagnosis was achieved in 500 (35%) patients after a median time of 206 days (IQR 60-533) [table 1 shows details and action taken following diagnosis for each indication subgroup]. At multivariable analysis, age and PR interval duration were significantly associated with the need for PM/ICD implantation among patients receiving ILR for RSUO whilst age was associated with AF detection among those with CRYSP (table 2). Conclusions In this cohort of patients use of ILR was associated with a good diagnostic yield regardless of the initial indication, triggered timely therapeutic actions and was overall safe.

Invasive risk stratification and implantable loop recorders in brugada syndrome: a single centre experience

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Risk stratification in Brugada syndrome (BrS) is challenging. Cardiogenic syncope, family history of sudden cardiac death and ECG markers are useful variables in determining patient risk. Invasive risk stratification is sometimes needed in those with an intermediate risk phenotype. Implantable loop recorders (ILR) may be considered in those patients with no inducible ventricular arrythmias during programmed ventricular stimulation (PVS). Objective The aim of this study was to retrospectively evaluate the outcome of BrS patients referred for PVS and ILR implantation. Methodology Demographic, clinical and follow-up data of BrS patients seen in clinic were retrospectively analysed from hospital databases. A p vale of &amp;lt;0.05 was considered significant. Results 129 patients have been diagnosed with BrS since launching the inherited arrhythmia clinic service (53.5% males). 15 (high risk patients) had an ICD (n=13, 10.1%) or PM (n=2, 1.6%) implanted because of a hospital cardiac arrest, ventricular arrhythmias, high grade AV Block or cardiogenic syncope. 26 (20.2%) were placed in the intermediate risk category, (65.4% males). Patients were offered an electrophysiology study (EPS/PVS) or an ILR depending on the clinical indication (Figure 1). Most were male (65.4%), with a mean age of 41.8±17.7 years at the time of risk stratification. 6 had a likely or definite pathogenic mutation (n=5 19.2% SCN5A, n=1 3.8% MYBPC3). This group had a median Shanghai score of 4.0±0.9. Gender (p=0.429), age (p=0.246), genotype (p=0.273) and shanghai score (p=0.746) did not differ between strategies. Most (n=12, 9.3%) were offered an EPS/PVS from the offset. Ventricular arrhythmias were induced in 1 (8.3%), an ICD was then implanted. The rest were implanted with an ILR on the day. Patients not offered an EPS (n=14, 10.9%) were initially implanted with an ILR because of insufficient grounds to proceed with an EP study. Patients with an ILR (n=25, 19.4%) were followed up for a median 39 ± 21 months. ILR monitoring identified actionable events in 3 (12.0%) patients. One (4.0%) needed a pacemaker for sick sinus syndrome. Two (8.0%) recorded non-sustained ventricular arrhythmias. Both were subjected to an EPS/PVS, one needed an ICD. None of the patients who had an EPS initially had any significant events during follow up. Conclusion ILR implantation has a role in risk stratifying intermediate risk patients who do not fulfil criteria for EPS referral. This may also be considered in intermediate risk patients who are not keen on an invasive risk assessment with EPS.

Invasive electrophysiology study guided loop recorder implantation in myotonic dystrophy type 1: a prospective single-center study

Abstract Funding Acknowledgements Type of funding sources: None. Introduction In one third of the patients with myotonic dystrophy type 1 (DMT1) the cause of death is of cardiac origin. The most common cardiac manifestations are arrhythmias and conduction disturbances. Purpose Due to its extreme long monitoring properties, implantable loop recorders (ILRs) are highly suitable to detect rare cardiac arrhythmias. To date, there are only limited data using ILRs in DMT1. We aimed to evaluate the role of the invasive electrophysiology study (EPS)-guided loop recorder implantation in patients with DMT. Methods In our prospective study 18 genetically confirmed DMT1 patients underwent non-invasive cardiac examination including transthoracic echocardiography, 24-hour Holter monitoring and surface ECG. In addition, EPS was performed in all cases to evaluate the risk of sudden cardiac death and infra-Hisian conduction properties. Based on the performed non-invasive diagnostic evaluation and EPS findings, patients were divided into low, intermediate and high-risk groups. For patients with normal investigation results and normal HV interval (&amp;lt;55 ms) only annual cardiac follow-up visits were planned (low-risk group). Patients with increased PR interval (&amp;gt;240 ms), QRS duration (&amp;gt;120 ms), or slightly prolonged HV interval (55-70 ms) underwent implantable loop recorder (ILR) implantation (intermediate-risk group). Permanent pacemaker (PM) or implantable cardiac defibrillator (ICD) was implanted in patients with 2nd/3rd degree atrioventricular block (AVB), significantly prolonged HV interval (&amp;gt;100 ms) or if sustained ventricular tachyarrhythmia could be induced during EPS. All patients were followed for at least 3 years. Results According to our study criteria, 8 patients could be categorized as "intermediate risk", 7 of them received implantable loop recorder (ILR). 1 ILR had to be removed 3 weeks after implantation due to skin infarction. During three-years of follow-up, 2 patients had many asymptomatic atrial high-rate episodes, but no 2nd or 3rd degree AVB, significant asystole or malignant ventricular arrhythmia were detected. Conclusions Our single-center prospective study examined the EPS-guided ILR implantation for the risk stratification of DMT1 patients for the first time. A more extensive, multicenter study is warranted to define optimal management of DMT1 patients with slightly impaired infrahisian conduction.

Early atrial fibrillation detection is associated with higher arrhythmic burden in patients with loop recorder after an embolic stroke of undetermined source

BackgroundAfter an embolic stroke of undetermined source (ESUS), long-term monitoring is recommended to start an anticoagulation therapy in patients with documented atrial fibrillation (AF). Literature is sparse about the AF burden following an ESUS, although this might have significant implications in terms of clinical management and therapeutic strategy. Our primary aim was to evaluate a possible association between early detection of AF (within 90 days from the ILR implantation) and higher AF burden. MethodsThis is a retrospective single-center study of 129 consecutive patients who received implantable loop recorders (ILRs) after an ESUS for detection of subclinical AF and their AF burden. ResultsMean age was 70.3 ± 10.4 years old (males: 51.9%). Atrial fibrillation was found in 40.3% of patients. Patients with AF were older, presented a higher CHAD2S2-Vasc Score and greater left atrial volume compared with patients without AF. The median AF burden was 1.2%; 59% of patients had the first AF episode within 90 days from the ILR implant while 41% experienced the first episode later than 90 days. The AF burden was significantly higher in the former group. Of note, the univariate analysis showed that only early AF detection was significantly associated with AF burden >1% (OR 20.0; 95% CI 1.68–238.6, p = 0.01). ConclusionsThe early AF detection was found to be significantly associated with a higher burden of AF.

Abstract WP33: Bedside Insertion Of Implantable Loop Recorders Prior To Hospital Discharge Improves Detection Of Atrial Fibrillation After Cryptogenic Stroke And May Reduce Stroke Recurrence

Atrial fibrillation (AF) is responsible for 15-20% of ischemic strokes. AF can be asymptomatic and remain undetected following acute stroke, initially classifying the event as cryptogenic. Implantable loop recorders (ILRs) provide long-term cardiac monitoring and are superior to traditional methods for detecting AF in patients with cryptogenic stroke. ILR placement is often performed by a cardiologist in an outpatient setting. Our institution identified that some patients were missing or cancelling appointments for device implantation. Failure to detect AF is associated with a greater risk of stroke recurrence. An interdisciplinary inpatient process was developed to place ILRs at the bedside on the stroke unit, prior to discharge. The purpose of the program was to increase patient compliance with ILRs, improve detection of asymptomatic AF, and reduce incidence of stroke recurrence through timely initiation of oral anticoagulants. To evaluate the program and provide recommendations, measures of success included rates of patient compliance with ILR implantation using inpatient vs. outpatient procedure and the percentage of patients who received a diagnosis of AF after ILR placement. Using 18 months of pre-implementation data as a benchmark, the average implant rate increased in the first 12 months following implementation. Of 97 patients who received ILR placement, nine (9%) have received a diagnosis of AF. Since three-year ILR monitoring has shown significantly higher AF detection than 30-day cardiac monitoring after cryptogenic stroke, more patients with AF may yet be identified. This presentation will demonstrate an increase in ILR implant rates and AF detection and highlight positive results using advanced practice professionals to perform the procedure. The program produced financial benefit and mitigated access to care barriers, with no poor outcomes or compromise in quality, and no negative impact on inpatient length of stay. In conclusion, bedside insertion of ILRs prior to discharge after cryptogenic stroke is a safe, efficient, cost-effective process that increases patient compliance when compared to outpatient return visits, improving detection of AF and prompt initiation of oral anticoagulants, and may reduce stroke recurrence.

Sex-based comparisons of clinical characteristics and outcomes of patients with embolic stroke of undetermined source with implantable loop recorders

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Embolic strokes of undetermined source (ESUS) constitute a significant proportion of all ischemic strokes, but sex-based comparisons of clinical characteristics and outcomes of ESUS patients have not been well explored. As such, we aimed to examine how sex influences outcomes of ESUS patients. Methods Retrospective cohort study performed on consecutive ESUS patients with an implanted ILR between December 2013 to September 2021. We obtained information on the patients’ characteristics, treatments, and outcomes from the electronic medical records. Cox regression was used to investigate whether sex was independently associated with outcomes. Results There were 176 patients included in this study. The mean duration of follow-up was 1254 ± 724 days. Mean age was 60.8 ± 12.0 and 47 (26.7%) of patients were female. On univariable Cox regression analysis for subsequent atrial fibrillation (AF) on implantable loop recorder (ILR), patients with subsequent AF on ILR were more likely to be female (HR 2.19, 95% CI 1.04–4.63, p = 0.040), older (HR 1.07, 95% CI 1.03–1.12, p = 0.001), have a lower glomerular filtration rate (eGFR) (HR 0.98, 95% CI 0.97– 0.99, p = 0.004), and have previous percutaneous coronary intervention (PCI) (HR 2.60, 95% CI 1.05–6.46, p = 0.039). On multivariable Cox regression, after adjustment for age, eGFR and previous PCI status, female sex remained independently associated with the development of subsequent AF on ILR. Female sex was not associated with other outcomes including mortality, subsequent acute myocardial infarction, stroke/transient ischemic attack and heart failure. Conclusions In this cohort of ESUS patients with ILR implantation, female sex was independently associated with a higher risk of development of AF on ILR. However, female sex was not a predictor of mortality, subsequent acute myocardial infarction, stroke/transient ischemic attack and heart failure.

An implantable loop recorder or smartphone based single-lead electrocardiogram to detect arrhythmia in adults with congenital heart disease?

The European Society of Cardiology (ESC) guidelines for the management of adult congenital heart disease (ACHD) recommend screening in patients at risk for arrhythmic events. However, the optimal mode of detection is unknown. Baseline and follow-up data of symptomatic ACHD patients who received an implantable loop recorder (ILR) or who participated in a smartphone based single-lead electrocardiogram study were collected. The primary endpoint was time to first detected arrhythmia. In total 116 ACHD patients (mean age 42 years, 44% male) were studied. The ILR group (n = 23) differed from the smartphone based single-lead electrocardiogram group (n = 93) in having a greater part of males and had more severe CHD and (near) syncope as qualifying diagnosis. In the smartphone based single-lead electrocardiogram group history of arrhythmia and palpitations were more frequent (all p < 0.05). Monitoring was performed for 40 and 79 patient-years for the ILR- and smartphone based single-lead electrocardiogram group, respectively. Arrhythmias occurred in 33 patients with an equal median time for both groups to first arrhythmia of 3 months (HR of 0.7, p = 0.81). Furthermore, atrial fibrillation occurred most often (n = 16) and common therapy changes included medication changes (n = 7) and implantation of pacemaker or Implantable Cardioverter Defibrillator (ICD) (N = 4). Symptoms or mode of detection were not a determinant of the first event. Non-invasive smartphone based single-lead electrocardiogram monitoring could be an acceptable alternative for ILR implantation in detecting arrhythmia in symptomatic ACHD patients in respect to diagnostic yield, safety and management decisions, especially in those without syncope.